CATV networks use an infrastructure of interconnected coaxial cables, signal splitters and combiners, repeating amplifiers, filters, trunk lines, cable taps, drop lines and other signal-conducting devices to supply and distribute high frequency CATV “downstream” signals from a main signal distribution facility, known as a “headend,” to the premises (homes and offices) of CATV subscribers. The CATV downstream signals operate the subscriber equipment, such as television sets, telephone sets and computers. In addition, most CATV networks also transmit CATV “upstream” signals from the subscriber equipment back to the headend of the CATV network. For example, the subscriber uses a set top box to select programs for display on the television set. As another example, two-way communication is essential when using a personal computer connected through the CATV infrastructure to the public Internet. As a further example, Voice Over Internet Protocol (VOIP) telephone sets use the CATV infrastructure and the public Internet as the communication medium for two-way telephone conversations.
To permit simultaneous communication of CATV upstream and downstream signals, and to permit interoperability of the subscriber equipment and the equipment associated with the CATV network infrastructure outside of subscriber premises, the CATV downstream and the CATV upstream signals are confined to two different frequency ranges. The CATV downstream signal frequency range is within the range of 54-1002 megahertz (MHz) and the CATV upstream signal frequency range is within the range of 5-42 MHz, in most CATV networks.
The CATV downstream signals are delivered from the CATV network infrastructure to the subscriber premises at a CATV entry adapter, which is also commonly referred to as an entry device, terminal adapter or a drop amplifier. The entry adapter is a multi-port device which connects at an entry port to a CATV drop cable from the CATV network infrastructure and which connects at a multiplicity of other distribution ports to coaxial cables which extend throughout the subscriber premises to cable outlets. Each cable outlet is available to be connected to subscriber equipment. Typically, most homes have coaxial cables extending to cable outlets in almost every room, because different types of subscriber equipment may be used in different rooms. For example, television sets, computers and telephone sets are commonly used in many different rooms of a home or office. The multiple distribution ports of the entry adapter deliver the downstream signals to each cable outlet and conduct the upstream signals from the subscriber equipment through the entry adapter to the drop cable of the CATV infrastructure.
In addition to television sets, computers and telephones, a relatively large number of other entertainment and multimedia devices are available for use in homes. For example, a digital video recorder (DVR) is used to record broadcast programming, still photography and moving pictures in a memory medium so that the content can be replayed on a display or television set at a later time selected by the user. As another example, computer games are also played at displays or on television sets. Such computer games may be those obtained over the Internet from the CATV network or from media played on play-back devices connected to displays or television sets. As a further example, signals from a receiver of satellite-broadcast signals may be distributed for viewing or listening throughout the home. These types of devices, including the more-conventional television sets, telephone sets and devices connected to the Internet by the CATV network, are generically referred to as multimedia devices.
The desire to use multimedia devices at multiple different locations within the home or subscriber premises has led to the creation of In-Home Entertainment (IHE) networks, which distribute multiple streams of In-Home Entertainment signals to the multimedia devices within the subscriber premises. Examples of home networking technologies that can be used to create In-Home Entertainment networks include Ethernet, HomePlug, HPNA, and 802.11n. In another example, the user data network may employ technology standards developed by the Multimedia over Coax Alliance. The Multimedia over Coax Alliance (MoCA) has developed specifications for products to create an In-Home Entertainment (IHE) network for interconnecting presently-known and future multimedia devices.
An IHE network uses the subscriber premise or in-home coaxial cable infrastructure originally established for distribution of CATV signals within the subscriber premises, principally because that coaxial cable infrastructure already exists in most homes and is capable of carrying much more information than is carried in the CATV frequency ranges. An IHE network is established by connecting IHE-enabled devices or IHE interface devices at the cable outlets in the rooms of the subscriber premises. The IHE devices and the IHE interface devices implement an IHE communication protocol which encapsulates the signals normally used by the multimedia devices within IHE signal packets and then communicates the IHE signal packets between other IHE interface devices connected at other cable outlets. The receiving IHE interface device removes the encapsulated multimedia signals from the IHE signal packets, and delivers the multimedia signals to the connected display, computer or other multimedia device from which the content is presented to the user.
Each IHE-enabled device is capable of communicating with every other IHE-enabled device in the in-home or subscriber premises network to deliver the multimedia content throughout the home or subscriber premises. The multimedia content that is available from one multimedia device can be displayed, played or otherwise used on a different IHE-enabled device at a different location within the home, thereby avoiding physically relocating the originating multimedia device from one location to another within the subscriber premises. The communication of multimedia content over the IHE network is considered beneficial in more fully utilizing the multimedia devices present in modern homes.
Since the operation of the subscriber premises IHE network must occur simultaneously with the operation of the CATV services, the IHE signals utilize a frequency range different from the frequency ranges of the CATV upstream and CATV downstream signals. A typical IHE signal frequency range is 1125-1675 megahertz (MHz).
In addition to traditional cable television service, a telephone service, known as “lifeline telephone service,” is also available to many CATV subscribers. Lifeline telephone service remains operative in emergency situations, even during a loss of power to the subscriber premises. An embedded multimedia terminal adapter (eMTA) device which includes a cable modem and a telephone adapter is used to receive the telephone service. The telephone service is typically implemented using a voice over Internet protocol (VOIP) communicated by the CATV upstream and downstream signals. Since the telephone service is expected to be available during a loss of power to the subscriber premises, CATV entry adapters adapted for use with an eMTA device have a passive port to which passive CATV upstream and downstream signals are conducted without amplification or other conditioning by an active electronic component. As a consequence, the loss of power at the subscriber premises does not adversely affect the communication of passive CATV signals to and from the passive port.
In addition to the passive port, CATV entry adapters typically have an active signal communication path which amplifies the CATV downstream signals and conducts them to a plurality of active ports of the CATV entry adapter. Subscriber equipment connected to the active ports typically benefits from the amplification of the CATV downstream signals. However, the loss of power to the entry adapter adversely influences the active signals conducted to and from the active ports through power-consuming components which become inoperative when power is lost. The communication of active CATV signals under power loss conditions is severely compromised or impossible.
Most eMTA devices used for passive CATV signal communication are not presently IHE-enabled. However, IHE-enabled eMTA devices are recognized as useful for expanding the number of multimedia devices in the IHE network. For example, telephony multimedia devices such as auxiliary telephone sets and answering machines could interact with an IHE-enabled eMTA device and provide telephony services throughout the subscriber premises. In order for multimedia devices to communicate with the IHE-enabled eMTA device, the CATV entry adapter must be capable of communicating IHE signals between the passive and active ports.
A disadvantage of implementing the IHE network with the in-home coaxial cable system is that the IHE frequencies have the capability of passing through the CATV entry device and entering the CATV network, where they may then pass through a cable drop and enter an adjoining subscriber's premises.
The presence of the IHE signals at an adjoining subscriber's premises compromises the privacy and security of the information originally intended to be confined only within the original subscriber premises. The IHE signals from the original subscriber premises, which enter through the CATV network to an adjoining subscriber premises, also have the potential to adversely affect the performance of an IHE network in the adjoining subscriber premises. The conflict of the signals from the original and adjoining subscriber premises may cause the IHE interface devices to malfunction or not operate properly on a consistent basis.
CATV networks are subject to adverse influences from so-called ingress noise which enters the CATV network from external sources, many of which are located at the subscriber premises. The typical range of ingress noise is in the frequency range of 0-15 MHz, but can also exist in other upstream or downstream frequencies. Ingress noise mitigation devices have been developed to suppress or reduce ingress noise from the subscriber premises before it enters the CATV network. The IHE frequency range is considerably outside the range of the normal ingress noise, and ingress noise suppression devices are ineffectual in inhibiting IHE signals. IHE signals, being outside of the CATV signal frequency range, may also constitute another source of noise for the CATV network. Separate IHE frequency rejection filters have been developed for external connection to CATV entry adapters. However, the use of such devices is subject to unauthorized removal, tampering, forgetfulness in original installation, and physical exposure which could lead to premature failure or malfunction.
Problems also arise because the CATV network and the in-home cable infrastructure were originally intended for the distribution of CATV signals to the cable outlets. The typical in-home cable infrastructure uses signal splitters to divide a single CATV downstream signal into multiple CATV downstream signals and to combine multiple CATV upstream signals into a single CATV upstream signal or range of signals. Distribution of the CATV signals to and from the cable outlets occurs in this manner. The CATV cable infrastructure was not intended for communication between cable outlets. But to implement the IHE communication protocol, the IHE signals must traverse between the multiple cable outlets by communication through each splitter in a traversal process referred to as “splitter jumping.”
The typical signal splitter has a high degree of signal rejection or isolation between its multiple output ports (the signal splitter output ports are also referred to as signal component legs). When the IHE signals jump the output ports of a splitter, the degree of signal rejection or isolation greatly diminishes the strength of the signals which effectively jump the output ports. The physical signal communication paths between the cable outlets are also highly variable because of the differences in the in-home cable infrastructure in most homes. The IHE communication protocol recognizes the possibility of variable strength signals, and provides a facility to boost the strength of IHE signals under certain circumstances. However, the substantial differences in the in-home cable infrastructure may nevertheless negatively impact the strength of the IHE signals conducted.
One example of significant negative impact on IHE signals arises from passive-active CATV entry adapters. Passive-active CATV entry adapters supply both passive CATV signals and amplified or active CATV signals at the subscriber premises for delivery to passive and active types of CATV subscriber equipment, respectively. Passive-active entry adapters include a splitter which essentially divides or branches the downstream signals from the CATV network into passive signals and into active signals. The passive signals are conducted through the entry adapter without amplification, conditioning or modification before they are delivered from a passive port to passive subscriber equipment, often the voice modem of a “life-line” telephone set. Because life-line telephone services are intended to remain useful in emergency conditions, the functionality of the telephone set cannot depend on the proper functionality of an amplifier or other active signal conditioner in the signal path. The active signals are conducted through a forward path amplifier, where the amplifier amplifies the strength of the signals or modifies or conditions some characteristic of the signals before delivery from active ports to active subscriber equipment. Because most subscriber equipment benefits from amplified signals, the majority of ports on a CATV entry adapter are active ports. Usually only one passive port is provided for each entry adapter.
In those situations where a CATV subscriber does not utilize the passive port for passive equipment, active equipment may be connected to the passive port and that active equipment may function properly if the strength of the signal from the passive port is sufficient. In other cases, the passive port simply may not be connected, and only the active ports of the CATV entry adapter are used.
Often attempts to connect the passive port as part of an IHE network will not be successful, however, because the IHE signals are severely diminished in signal strength when they pass from the active ports in a reverse direction through the forward path amplifier. The IHE signals must pass in a reverse direction through the forward path amplifier to reach the splitter of the CATV entry adapter before the IHE signals can jump the splitter and reach the passive port. Signal conductivity in the reverse direction through a forward path amplifier is simply not possible without severe attenuation. Thus, it has been difficult to use a passive port on a CATV entry adapter for connection in an IHE network, because of inadequate IHE signal strength. The level of attenuation is greater than can be overcome by adjusting the boost of the IHE signals in accordance with the IHE communication protocol.